Standardized grey scale ultrasonography in Graves' disease: correlation to autoimmune activity

Abstract

OBJECTIVE: Graves' disease leads to thyroid enlargement and to reduction of tissue echogenicity. Our purpose was to correlate grey scale ultrasonography of the thyroid gland with clinical and laboratory findings in patients with Graves' disease. DESIGN: Fifty-three patients with Graves'disease were included in our study, 100 euthyroid volunteers served as control group. Free thyroxine (FT(4)), TSH and TRAb (TSH receptor antibodies) values were measured and correlated with sonographic echogenicity of the thyroid gland. METHODS: All patients and control persons underwent ultrasonographical histogram analyses under standardized conditions. Mean densities of the thyroid tissues were determined in grey scales (GWE). RESULTS: Compared with controls with homogeneous thyroid lobes of normal size (25.6 +/- 2.0GWE, mean +/- S.D.) echogenicity in patients with Graves' disease was significantly lower (21.3 +/- 3. 3GWE, mean +/- S.D., P < 0.0001). Among the patients with Graves' disease significant differences of thyroid echo levels were revealed for patients with suppressed (20.4 +/- 3.1 GWE, mean +/- S.D., n=34) and normalized TSH values (22.5 +/- 3.6GWE, mean +/- S.D., n=19, P < 0.02). Significantly lower echogenicities were also measured in cases of persistent elevated TRAb levels (19.9 +/- 2.9GWE, mean +/- S.D., n=31) in comparison with normal TRAb levels (22.9 +/- 3.5 GWE, mean +/- S.D., n=22, P < 0.0015). No correlation could be verified between echogenicity and either still elevated or already normalized FT(4) values or the thyroid volume. In coincidence of hyperthyroidism and Graves' ophthalmopathy (19.7 +/- 3.5GWE, mean +/- S.D., n=23) significantly lower echogenicity was measured than in the absence of ophthalmological symptoms (22.3 +/- 3.3GWE, mean +/- S.D., n=30, P < 0.016). Patients needing active antithyroid drug treatment revealed significantly lower thyroid echogenicity (20.3 +/- 3.1 GWE, mean +/- S.D., n=40) than patients in remission (23.7 +/- 3.4 GWE, mean +/- S.D., n=13, P < 0.001). Statistical evaluation was carried out using Student's t-test. CONCLUSIONS: Standardized grey scale histogram analysis allows for supplementary judgements of thyroid function and degree of autoimmune activity in Graves' disease. Whether these values help to estimate the risk of recurrence of hyperthyroidism after withdrawal of antithyroid medication should be evaluated in a prospective study.

The association between hypoechogenicity or irregular echo pattern at thyroid ultrasonography and thyroid function in the general population

“…A trend towards a high occurrence of decreased echogenicity among the participants with overt biochemical hyperthyroidism was found, but did not reach significance in this limited group. An association between the two has previously been demonstrated (17). One study examined apparently healthy subjects using hospital staff in a 3-year follow-up (2).…”

A hypoechoic pattern of the thyroid at ultrasound does not indicate autoimmune thyroid diseases in patients with morbid obesity

“…In order to minimize the operator variability in assessing thyroid echogenicity, only those scans performed by the same operator (S C), who was well trained and had a 5-year experience in thyroid imaging, were selected. According to previous studies, echogenicity was evaluated in both thyroid lobes and in the surrounding neck muscles on the transverse section (12,16). The isthmus was excluded to avoid the interference of reflecting echoes from the tracheal cartilage.…”

“…The isthmus was excluded to avoid the interference of reflecting echoes from the tracheal cartilage. Hypoechogenicity was ascertained by comparison of the echo distribution in the thyroid parenchyma with respect to the surrounding neck muscles, and only those scans showing mild to severe generalized hypoechogenicity were selected (12,16).…”

“…In autoimmune thyroid diseases (AITDs), however, both lymphocytic infiltration and disruption of normal tissue architecture cause a reduction in thyroid echogenicity (1,4,6,10,11). Thyroid hypoechogenicity is currently viewed as an early sign of thyroid autoimmunity, which may be present even when the thyroid disorder is not suspected from a clinical point of view (4,6,7,12,13). Rapid improvements in US equipment and the use of standardized computerized algorithms have permitted an objective and quantitative measurement of tissue echogenicity in thyroid diseases (11)(12)(13), as well as in other pathological conditions (14,15).…”

“…Rapid improvements in US equipment and the use of standardized computerized algorithms have permitted an objective and quantitative measurement of tissue echogenicity in thyroid diseases (11)(12)(13), as well as in other pathological conditions (14,15). Using a subjective measure of thyroid echogenicity, previous studies demonstrated that in patients with thyroid autoimmune diseases, the presence of circulating thyroid antibodies (Abs) as well as the development of hypothyroidism was closely correlated with the degree of thyroid hypoechogenicity (1,5,11,12,16).…”